Power-operated toolholder



June 9, 1953 L. E. LEE 2,641,151

POWER-OPERATED TOOLHOLDER `Filed. Feb. a, 1949 1o sheets-sheet 1 INENTOR 'LUTHER LEE ATTORNEY June 9, 1953 Filed Feb. 8, 1949 FIG. 2

L. E. LEE

POWER-OPERATED TOOLHOLDER 1o sheets-sheet a INVENTOR LUTHER E. LEE

Y fr@ @HM ATTORNEY Filed Feb. s, 1949 1o sheets-sheet a June 9, 1953 l..E. LEE 2,641,151

POWER-OPERATED TOOLHOLDER LUTHER JXNTEE ATTORNEY June 9, 1953 L. E. LEE

POWER-OPERATED TOOLHOLDER Filed Feb. 8, 1949 FIG. 4

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10 Sheets-Sheet 4 INVENTOR LUTHER E. LEE

j@ (9K/LLM ATTORNEY June 9, 1953 l.. E. LEE 2,541,151

' PowER-oPERATED TooLHoLDER Filed Feb. 8, 1949 10 Sheets-Sheet 5ATTORNEY June 9, 1953 l.. E. LEE

-PowER-OPERATEDv TooLHoLDER 10 4Sheets-Shea?I 6 l Filed Feb. 8, 1949 FIG. '6

L lla INVENToR my E. EE

BY Q @Aa V. E N m June 9, 1953 L. E. LEE 2,641,151

POWER-OPRATED TooLHoLDER Filed Feb. 8, 1949- 1o sheets-Sheet 7 FI/G. l 7

' INVENTOR LUTHER: E. LEE

ATTORNEY June 9, 1953 L. E. LEE 2,541,151

POWER-OPERATED TOOLHOLDER Filed Feb. a, 1949 1o sheets-sheet e INVENTORLUTHER E LEE ATTORNEY June 9, 1953 Filed Feb. e, r1949 L. E. LEE

POWER-QPERATED TOOLHLDER 10 Sheets-*Sheet 9 ArroRNEY Janes, 1953 1 2L,E, EE 2,641,151

POWER-OPERATED TOOLHOLDER Filed Feb. 8,. 1949 Y 10 Sheets-Sheet 10 F I6.l2

INVENTOR LUTHER E. EE

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ATTORNEY Patented June 9, 1953 UNITED YSTATES PATENT OFFICE 16 Claims.(Cl. 82-21) (Granted under Title 35, U. S. Code (1952),

sec. 266) The present invention relates to too1 holding heads formachine tools such as planers,iboring mills, lathes, slotters and thelike and more particularly to a tool holding head which will position acutting tool for cutting at various levels during a continuous workingstroke.

The device of the present invention may be used With particularadvantage in machining workpieces of large and complicated design. Suchworkpieces may be built up in skeletonized form by a Welding process ormay be in the form of large castings or the like. Large Workpieces ofthis character ordinarily require machining operations upon a number ofaligning bosses or mounting pads and each of these must, as a rule, beindividually machined since they lie in different planes or, even thoughthey may lie in the same plane a reinforcing rib or other obstructionmay be located between the surfaces so as to prevent theirboth beingmachined in one operation. As is well known in the art, when workpiecesof this type are being machined it is always preferable to take roughingcuts on all of the surfaces before taking any finishing cuts in order toallow for distortion due to Warpage or possible movement of theworkpiece during the roughing operations. Thus, it lcan be seen thatindividual machining of the surfaces normally requires a large number ofsetups or tool changes and is slow, tedious and expensive.

This invention contemplates the provision of a head having a moveableholder for the usual cutting tool and, in the present embodiment, suchhead is shown adapted for movement of the tool holder by compressed air.The head may be secured to the usual clapper box, or tool post and thecutting tool may be extended a measured amount to machine a surface inone plane, may be retracted to clear an obstruction and may then beextended to cut in the same or a predetermined diierent plane all duringone continuous working stroke so as to continue the machining operationwithout interruption.

It is therefore an object to provide means automatically to retract acutting tool in order to permit it to hurd-le an obstruction and then toreturn the tool to its original or a predetermined different cuttingposition without interruption during the working sroke.

A further object of the present invention is to provide a cutting toolholder which can be set to automatically move to a plurality ofpredetermined positions in sequence during a continuous working stroke.

Still another object is to provide automatic to control the positioningof the cutting tool atl predetermined positions.

An additional object is the provision of novel means for bufling thecutting tool holding ram in its retracting movement and for accuratelylocating the tool in retracted position.

Another object is to provide a tool actuating device that may be quicklyand easily installed on a conventional machine tool without structuralmodiiication and which may be used at maximum cutting speed for theparticular material being machined. By the present invention the numberof work setups and tool changes is materially reduced and the workoutput per manhour may be substantially increased.

Other objects and advantages will be hereinafter more fully describedand for a complete understanding of the nature, scope andcharacteristics of this invention reference may now be had to thefollowing description and accompanying drawings in which latter:

Fig. 1 is a fragmentary perspective view of one embodiment of thepresent invention showing a tool holding head and control valve mountedupon a planer;

Fig. 2 is an end elevation of a planer upon which two tool holding headsof the present invention and two conventional tool holders have beeninstalled for simultaneous operation upon a workpiece;

Fig. 3 is a fragmentary perspective view of the tool holding head andcontrol of Fig. 1 shownmounted upon a vertical boring mill;

Fig. 4 is a sectional view taken substantially along the longitudinalaxis of the tool holding head illustrated in Figs. 1, 2 and 3 andshowing the tool holding ram in the extended position;

Fig. 5 is a detailed enlargement of the upper taken along a linesubstantially corresponding to line 9 9 of Fig. 5 and showing thedetails of the spacing block positioning or indexing device;

Fig. 10 is an enlarged side view partly broken away of the indexingmechanism shown in Fig. 9;

Fig. 11 is a detailed perspective view with a portion cut away, showingthe construction of the stop pin indexing mechanism;

Fig. 12 is a vertical sectional view partly in elevation of oneembodiment of the fluid pressurer control valve employed in the presentinvention;

Fig. 13 is an end elevation of the control valve shown in Fig. 12,showing a trip lever detent; and

Fig. 14 is a top plan view of the end of the trip lever shown in Figs.l2 and 13.

Referring to the drawings in detail; Figs. 1, 2 and 3 show how a head 20of `the' present invention may be suitably mounted on the usual toolsupport or clapper box 2| of a machine tool such as a planer 22 (Fig. 1lor a vertical boring mill 23 (Fig. 3) and connected by a hose 24 with afluid pressure control valve 25. This valve is preferably positionedadjacent a workpiece support or table such as the reciprocating table 26of the planer, (or the rotating table 21 of the vertical boring millFig. 3), so that the valve operating lever |40 may be actuated by cam 29carried by the work` table. Air under pressure is supplied to the valve25 through an inlet hose 30 from any u suitable source.

An indexing device 3| may be provided as a part of the `head structureas will hereinafter be described in detail and this indexing device maybe operated by the air impulses controlled by valve 25 to position spaceblocks of selected length so as to accurately limit the movement of thecutting tool toward the workpiece.

The planer table may support a number of workpieces A, 'A' and B asillustrated in Figs. 1 and 2 and the vertical boring mill may have aworkpieceC suitably mounted thereon.

Referring in detail to Figs. 4, 5 and 6 wherein the 'interior of a toolholding head is illustrated, the lower portion of the head 20 is widenedto provide a mounting pad 32 having spaced mounting bolt receivingopenings 33. A central vertical bore 34 is provided in the head and theupper part of the bore is enlarged at 35.

A ram 36 is shown vertically movable in said bore and has an enlargedhead 31 located within the enlargement 35. A keyway 38 formed in head 31is adapted to slidably engage key 33 for preventing rotational movementof ram 36. The lower end of the ram carries a' tool 40 secured in placeby set screws 4|.

Extending upwardly from the upper end of. the ram 36 and firmly securedthereto Visv a piston shaft 42 which is threaded at its upper end toreceive a spring retaining nut 43 and is surrounded by a compressionspring 43a. A piston 44 is mounted on the shaft 42 above the nut 43 andis retained in place by a large nut 45, This piston may be provided withone or more piston rings 44d as illustrated. The depending piston skirt46 has integral therewith a pair of oppositely extending lugs 41, whichin use engage with suitable stop pins to determine the position of thecutting tool in a manner hereinafter discussed in detail.

Piston skirt 4S continues downwardly and is received within a guidebushing 48 which bushing is supported by threaded engagement with theupper end of the mounting pad 32. The upper end of guide bushing 4S isprovided with opposed slots 49 as shown particularly i'n Fig. 9 and thelugs 41 are guided therein in their vertical movement. The lowermost endof the guide bushing 48 is turned in at 53 to form a ledge for thesupport of a shouldered buffer bushing or bearing 5| which is recessedto receive the lower end of the spring 43a. Bushing 5| projects a shortdistance below the undersurface of inturned ledge 50 and, at the end ofthe retracting movement of ram 3S, the undersurface 0i" this bushing isstruck by the upper face 31a lof enlarged head 31. When this occursspring 43a. is supported between nut 43 and buffer bushing 5| abuttingagainst face 31a and hence no longer urges the ram upwardly. Thisfeature, possibly in combination with the residuum of air being ventedfrom chamber |01 cushions the ram as it approaches the upper limit/ofits retracting movement. In practice it has been found that the top ofthe ram never strikes the undersurface of ledge 5U though bushu ing 5|projects only. about lAz" beyond the underblocks are arranged in pairson the upper surface' of rotary ring 52 to which they may be secured byany suitable means such as retaining screws 5t. These spacer blocks arein pairs of equal length and are mounted upon the upper surface of thering so that the two members of each pairv are spaced 180 apart aroundthe surface of the ring. Thus bloeit 51 is the same height as block 58(not shown), block 53 is the same height asv block E0, block 6| is theexact height of block 62 etc., all around the ring until the embodimentillustrated 8 pairs of blocks are provided spaced at 180 intervalsaround the ring.

If desired, the spacer blocks may be formed of a number of layers asillustrated in Fig. '1. In this event the desired length may be obtainedby a combination of blocks selected from a kit containing accuratelypre-ground blocks of such variety of thicknesses that any desired lengthof block may be obtained by proper combination. As illustrated in Fig.'7 such built-up blocks include a threaded spacer 13 on top and one ormore spacers 14, 15 and 16 thereunder, each centrally apertured toreceive the retaining. screw 5B. The use of such multipart blockseliminates the need for accurately finishing special blocks for eachjob.

if desired an alternative form of nxed spacing member may be employed asillustrated in Fig. 8. This member comprises a ring 11 split to permitassembly about the guide member 48 and secured together at the points ofContact by suitable fastening means such as screws 18 only two of whichare shown. Ring 11 is secured by screws 56 to a toothed indexing ringsimilar to the toothed portion of ring 52. As noted the upper surface ofthe split ring 11 has a plurality of steps of equal height disposed onopposite sides of the ring. Thus step 'i9 is the same height as step EE,etc. The use of such integral ring type spacing block may beparticularly convenient where large quantities of workplaces are to bemachined or where there are repeated shop orders for a particularworkpiece.

It will be apparent that rotation of ring 52, Figs.

As there shown a,Y

9 and 11, `successively, .positions different pairs of spacer blocksunderthe oppositely extending lugs 41 mounted'upon the piston skirt 46;consequently, by rotating the ring 52 to bring `selected pairs of suchblocks under the lugs, the descent of the piston skirt 46 and/itsattached piston shaft;42 and ram 36 can accurately be limited inaccord.- ance with predetermined measurements. Slot 8| inthe upper partof head member 32 registers with notch 82 in ledge 50 to provide accessto the undersidev of the spacer block anchoring screws 56. By rotatingring 52 each of these screws 55 may successively vbe brought intoregistry with said notch-so as to facilitate removal and replacement ofsuch blocks. In order automatically Vto position successive pairs ofspacer blocks under the lugs 41 thereiis provided the indexing mechanism3| lshownw in Figs. 9, l and 1l and which comprises a laterallyextendinghousing 83 supported on pad 32a and bored to provide acylinder84 in which piston 85 secured to fa piston shaft 86reciprocates. Compression spring 81 surrounds shaft 83 and .normallyurges the piston 85 and shaft 86 to the left. 'I'his piston ispreferably a slightly loose t in the cylinder to assure easy action andthe .forward end of the piston is chamfered at 88 to provide a facewhich will seat against a correspondingly chamfered f-ace 89 toeffectively seal the parts against the escape-of air past the pistonwhen the piston is in its extreme right-hand position. A threadedbushing 99 guides the shaft 86 and forms -an abutment for spring 01.

A pawl or step by step indexing mechanism is provided on the right-handend of shaft 86` and f' includes a'guide block 9 I, one side 92 of whichrides in a groove 93 in a side plate 83a to restrain the piston shaftfrom rotation. A portion of guide block 9| extends on the opposite sideof the piston shaft 86 to form an abutment94. A toe 95 is slotted toextend on both sides of guide plate 9| and is hingedly mountedthereto at96. A small wire spring 91 normally urges this toe into engagement withthe abutment 94.

The stop supporting ring 5,2 is provided around its lower periphery witha plurality of teeth, one of which, tooth 90, is shown seized betweenbetween the tip of the toe 95 and the tip 99 of a detent arm |00pivotally mounted at IIJI. With the piston shaft 86 in'its extendedposition as shown in Figs. 9 and 10 the end- |02 of the guide plate 9|bears against the heel |03 of the detent arm |00 causing it to pivotaround fulcrum |0| to urge the tip 99 of the detent arm |00 intopositive engagement with one side of index tooth 198. In the indexingoperation it will bey noted that an impulse of air entering the bore ofthe housing 83 through coupling |04 will force piston 85 to thek rightcausing toe 95 to engage one side of an index tooth and rotate thespacer block supporting ring 52 to position a new set of blocks underthe piston movement limiting lugs 41. vi When the air is vented from theindexing cylinder. 84 the piston 85 will be returned to the left bycompression spring 81 and toe 95 will pivot about point 96 to clear thenext succeeding tooth |05. Once clear spring 91 will snap the toe backinto engagement with abutment 94 so that the next impulse of air in theindexing cylinder will move the next tooth |85, into the position'formerly occupied by tooth 98.

Since detent |00 is free to pivot around fulcrum point IIlI when end |02is clear of the detent heel |03, the detent tip 99 will not interferewith the rotation of ring 52 until the piston again reachestheright-handlimit of its movement and a new tooth is engaged betweenthe detent tip '99 and toe 95. A lubricant fitting |06 is provided asshown.

Referring again tov Figs. 4, and 6 it Will-be noted that air hose 24leads into the hollow cylinder |01 formed withinthe piston receiving cap|08 and, by opening a thumb valve 09 communication is afforded through apipe Il!) to the operating cylinder of the indexing mechanism'.

A stroke adjuster and auxiliary s buffer is mounted in the upper part ofthe cap |08 and includes a hollow stem I threaded into the cap andretained in position by lock nut I2. Packing I lprevents leakage. Anextension I I4 is threaded into the lower end of stem I|| and supports amushroom type valve ||5 mounted for axial movement therein. Compressionspring I6 normally urges this valve downwardly to seat itin the mannerillustrated in Figs. 4 and 5. A buffer cap I I1 is tted around theextension I4 with a very slight clearance and has a central aperture |8through which air may be admitted tothe chamber formed between theinside wall of the cap and the undersurface of extension I |4. The stemof valve I I5 is preferably notched or grooved so that aperture ||8 isnot fully closed by the seating of the valve stem thereagainst therebyallowing air to enter chamberl when valve I I5 is unseated. A pin I I 9projecting from extension E62 engages in a slot |20 in the cap to retainit in place.

As illustrated in Fig. 6 the head of lstem I'I I may be provided withgraduations about its periphery which may be read against a pointer |2Ito indicate the relative axial displacement of buier cap I1 thebottomsurface of which is contacted by nut 45 in retracted position.Pointer I2I may be pivoted at |22 so that it may be swung back out ofthe way to adjust locking nut I I2.

The air control valve is illustrated in detail in Figs. 12 and 13 andcomprises a body block |23 suitably apertured to receive a fluid inletfitting such as valve |24 and a fluid outlet tting |25 which connects tothe air hose 24 leading to the tool operating head.

An air inlet valve |25 of the inverted mushroom type is mounted in block|23 so that its head |21 engages a seat |28 to control the ilow of airfromv the supply line 38, through a portion of bore |29, and through airhose 24 to the tool supporting head. The stem of valve |26 passesthrough a packing bushing |30 and is threaded to receive a nut |3| whichcompresses a spring |32 to normally urge the valve upwardly into aclosed position. The block |23 also contains a vent valve |33, similarin construction to inlet valve |26, and having a head |34 which is urgedagainst seat |35 by the tension of spring |36 normally to seal oi bore|29 and prevent the escape of air therefrom. However, during the ventingmovement of this valve it is moved downwardly away from the seat and airis permitted to escape from hose 24 through bore |29, channel |31,passage |38 and petcock |39 into the atmosphere.

A. valve actuating mechanism is located on top of the block |23 andcomprises an elongated trip lever |40 fulcrumed on a pivot |4| andreinforced against side thrust by spaced guide blocks |42 and |43extending upwardly from the block |23. The portion of this lever to theleft of the fulcrum contacts the rounded upper end of air valve |26 andthe portion of the lever to the right of the fulcrum bears against therounded upper lendV of vent valve |33. A compression spring |44 normallyurges the left end of the trip lever upwardly and is sufficiently strongto overcome spring |36.

The outermost end of the trip lever is hori- 'zontally slotted at |45 toprovide spaced upper and lower projections |46 and |41, respectively. Aroller supporting latch member |48 has a hori- Zontal tongue |49 whichenters the slot |45 and is pivotally secured by a vertical pin |50. Theupper end of this pin extends beyond projection |46 and terminates in ahead |51 which retains a coil spring |52 in place about the upperportion of the pin. One end of the coil spring |52 is anchored to amooring post |53 affixed to the lever |40 and the opposite end of thespring is turned downwardly at |54 and passes through a small hole inthe latch member 48. This hole extends all 'the way through the latchmember so as to permit reversal of the parts. The latch member supportsupper and lower rollers |55 and |56 for rolling engagement with aregulating means or tripping cam 29 which may be secured to the worksupporting table for movement therewith. Latch |48 has a pad portion |51which normally bears against the side of lever |40 by the pressure ofspring |52 but yieldingly permits displacement when an obstruction isencountered in one direction.

As illustrated in Fig. 13 a plate |58 may be pivotally secured at itslower end by screw |59 to one y This plate |58 is preferably of theL-shape illustrated so as to clear the venting petcock |39. A flatspring |6| formed as shown normally urges the ledge |60 under the triparm l|48 and this spring is secured in piace by pin |62 and screw |63.Plate |50 may be used with special advantage on long cuts such as themachining operation shown in Fig. 3. When not being used, plate |58 maybe swung to the right and secured against pivotal movement in thatposition by screw |10 shown in place in Figs. 12 and 14. This screw |10extends through a hole Ill in plate |58 and is threaded into block |23at |12.

In the event it is desired to reverse the working stroke of the machinetool the latch member |43 is removed by extracting pin |53 and spring|52, turning the latch member |40 upside down and replacing the pin andspring. In this reversed position the pad |51 lies on the opposite sideof trip lever |40 and spring |52 yielding'ly permits the latch to pivotin the opposite direction. 'The plate |58 can be reversed by simplyremoving pivotv screw |59, turning over vthe plate and replacing thescrew. The spring |61 `can likewise be reversed and held in its reversedposition by screw |6311. The body of the plate |58 then lies on theopposite side of the trip arm |40 and latch |48.

Operation In the use of the foregoing invention the machine such as aplanar, vertical boring mill, etc., rst has the workpiece or workpiecesto be machined installed thereon and secured in place. Next the toolholding head 26 is mounted on the usual clapper box or tool post asillustrated in Figs. 1, 2 and 3 and valve 25 is secured adjacent thepath of movement of the work supporting table. A cam Y29, of suitablelength, is then attached to the edge of the table 'in such a manner thatits sloping forward end will engage the lowermost roller of vlatch |48to raise the outer iii) 8 endv of lever |40. The rear end of cam 29 isnot sloped but terminates in a sharpA edge to'cause the latch to dropoff abruptly and thereby cause a rapid closing ofA inlet valve |26 andopening of vent valve |33.

In installing the present invention the spacer blocks and, when used,the auxiliary buffer are next adjusted to position the tool for cuttingin the desired planes. The spacer blocks may readily be removed byloosening lock ring |64 (Figs. 4, 5, 6) and raising the cylindricalcover |65 so as to expose the spacer block supporting ring 52. Sincethis ring 52 is retained in its lowermost position only by the springpressed detent 54 it may readily be moved upwardly to provide accessfrom below to the heads of the spacer block anchoring screws 56. Ifdesired the heads of these screws may individually be positioned abovethe slot 8| to permit access from below. The proper stop pins accuratelyground to the desired length may then be installed in 180 spaced pairsabout the ring and, if less than 8 cuts are to be made then duplicatesets of stops of the desired length may be installed. Where the numberof steps to be machined is 2, 4 or 8 it will be obvious that the desiredaccurate repetitive positioning of the cutting tool can be achieved bysimply duplicating spacer blocks of the required length as desired.However, where an off number such as 3, 5, 'l or 9 diiierent planes areto be machined without interruption then the combined stroke adjusterand buffer mecha-v nism contained in the cap |08 may be used to positionthe tool for the odd cutting steps.

The stroke adjuster may be set by bodily rotation of screw to move theentire mechanism into or out of the cap |08. It will be apparent that ithree surfaces are to be machined then the buffer mechanism may beadjusted to position the ram in a desired plane when it is in itsretracted position and a cut may be made with the ram so retracted.

The machine may then be placed in operation causing the desired movementof the work table. In the installation illustrated in Figs. 1 and 2 thiswill be a reciprocating movement and the table supported cam 29 willsuccessively raise and release the trip lever of air control valve 25 toalternately build up and release air pressure in line 24 leading to thetool holding head 20. The impulse of air under pressure arriving throughhose 24 passes downwardly through valve |09 and pipe |0 to the indexingcylinder 84 where it lbears against index piston 85 and moves it to theright end of the cylinder as shown in Fig. 9 compressing index spring 81and moving piston shaft 86 to the right. Toe 95 havingv engaged tooth 98rotates the ring 62 one-sixteenth of a revolution to bring a set ofspacer blocks under the oppositely extending piston supported lugs 41.Overtravel of the ring is prevented by tip 99 which engages the oppositeside of tooth 98 and forms a part of arm |00 pivoted in the indexhousing 83. This tip is retained in its tooth engaging position by theoppositely extending body portion |03 against which heel |02 bears. Asair pressure builds up in the index chamber the tooth 98 is securelyclamped between toe 95 and tip '99.

This impulse of air also builds up ,pressure in chamber |01 to forcepiston 44 downwardly, however, the indexing step is taken before thepiston 44 commences its downward movement since the area of the indexingpiston and the strength of its springl are so proportioned that 9 arelatively small pressure, preferably on the order of 13 pounds persquare inch is sufficient to complete the indexing operation.

When the pressure increases in chamber |01 to preferably something over26 pounds per square inch piston 44 starts to move downwardly andcarries piston rod 42 connected at its lower end to ram 35. Ram 36carries cutter bit 40. When a pressure of about 50 pounds per squareinch has built up in chamber |01 the oppositely extending lugs 41 strikethe upper surface of the particular space blocks located thereunder tohalt the descent of the piston and to position tool 40 in the desiredplane for the initial cutting stroke. Lugs 41 do not strike against thespace blocks with any force. Instead they at rst touch rather lightlyand then, as the pressure in chamber |01 increases, the piston is urgeddownwardly with an ultimate pressure of 90 pounds or more per sl'iuareinch. With a piston area of about 4 square inches this amount ofpressure is suflicient to positively hold the piston, ram and cutter inthe desired plane with sufficient force to rigidly support the toolduring its cutting operation. The area of the index piston 85 may beabout @A of one square inch in the embodiment illustrated but the indexspring is so proportioned that the indexing step is completed before theram movement starts.

As the incoming air under pressure enters s chamber |01 a portion ofthis air also passes into the buier unit through opening |I8 and pastmushroom valve |5 which is forced upwardly to permit air pressure tobuild up in chamber |66 provided in the handle of buffer control knob i|61. When pressure within chamber |66 equals the pressure in chamber |01valve ||5 is closed by spring ||6 and the buffer cap ||1 is held in itslowermost position by the stem of valve ||5 bearing thereagainst.

When the trip lever drops oif the end of the cam 29 secured to thetable, inlet valve |26 closes and vent valve |33 opens. 'Thisimmediately releases the pressure in chamber |01 at a rate which isdependent upon the adjusted position of petcock |39..

Compressed spring 43a thereupon rapidly raises piston 44,- retractingram 3,6, This retraction continues until the upper end 31a of the ramstrikes the undersurface of buffer bushing 5| which moves upwardly a fewthousands of anl inch to cushion the blow. In the event the strokeadjuster and auxiliary buifer is employed, then that device is screweddown until the upper end 31a of the ram will not strike buffer bushing5| but instead the top of the piston retaining nut strikes theundersurface of the buffer cap ||1 unseating the valve ||5 upwardly. Asvalve H5 is unseated the air under high pressure in chamber |66 rushesout to fill the space within the buffer cap and cushion the upwardmovement of that cap. This buiiing action is only momentary since theexcess pressure rapidly escapes through the space left in the loose fitbetween the periph-` eral wall of the lower end I4 and the inner wall ofthe buffer cap |1 By the above action it will be noted that the movingram assembly does not strike its limit stops with great force at eitherextent of its movement, and vibration, wear and resulting inaccuracy isaccordingly avoided.

In connection with the valve operating cam 29- it should be noted thatin machining workpiecesl having several relatively short' pads orbossestov be machined an individual cam may be attached to the worktable for each pad, each such cam, of course, being of suitable lengthand positioned to hold inlet valve |26 open so that tool 40 will bemaintained in cutting position for the particular pad. However, insteadof using several individual cams a piece of angle iron of suitablelength and having several appropriately spaced camming surfaces formedon the horizontal ledge thereof may be attached to the work table. 'ihislatter arrangement is of particular advantage where large productionruns are to be made and it is necessary to completely dismantle thesetup from time to time.

In machining operations such as that illustrated in Fig. 3 where thesurfaces to be machined are relatively long and suitable cams of therequired length might be costly, a short cam 29 and a tripping ringer|58 may be used in conjunction with pivot plate |58 in place of the typeof cam described above. This ivot plate as previously explained inconnection with Fig. 13 may be used to retain valve |26 in open positionthereby subjecting piston 44 to constant pressure from the air source.When this pivot plate is used, a short cam 29 is secured to the table insuch position with regard to the surface to be machined that it willengage latch |48 to momentarily raise the outer end of lever |40 therebypermitting pivot plate |58 under the tension of spring I6 to swing intoretaining position. At the end of the cutting action on the particularsurface, trip nger |68 carried by the table strikes the tip |69 of plateE58 to swing the pivot plate to the right as viewed in Fig. 13 and allowthe outer end of lever |40 to drop down under the influence of spring|44 to close valve |25 and open vent valve |33.

Although the foregoing description has been conned to the application ofthe present invention to planers and boring mills it is to be understoodthat there are a wide variety of machining operations performed on theseand other types of machine tools in which the disclosed apparatus can beused with considerable advantage. It is believed that with thedescription of this invention at hand it will be readily apparent tothose skilled in the art as to how to adapt this apparatus to therequirements of the particular machining operation.

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

l. A cutting head and control for use on a machine tool wherein relativemovement is effected between a Vcutter and a workpiece comprising, asupport, a cutter controlling ram movable on the support, means foralternately extending and re- .be extended a variety of distances tomachine portions of a workpiece in different planes during a continuouscutting stroke. 2. A pneumatically operable head for supporting a cutteron a machine tool comprising, a housing, a reciprocable cutter supportmounted in said housing, resilient means urging said support upwardly toretract the cutter from a workpiece, a uid connection to supply fluidunder pressure to the interior of said housing to force the cuttersupport downwardly against the resilient means, and a combined bufferand stroke adjuster mounted in said housing and extensible against theupper end of the cutter support to adjustably limit said support in itsupward movement.

3. A pneumatically operable head for supporting a cutter on a machinetool comprising, a housing, a reciprocable cutter support mounted insaid housing, resilient means urging said support upwardly to retractthe cutter from a workpiece, a fluid connection to supply iiuid underpressure to the interior of said housing Ato force the cutter supportdownwardly against the resilient means, a combined buffer and strokeadjuster mounted in said housing and extensible against the upper end ofthe cutter support to adjustably limit said support in its upwardmovement, and means for indicating the adj-usted position of saidcombined buier and stroke adjuster,

4. A pneumatically operable head for supporting a cutter on a machinetool comprising, a housing, a reciprocable cutter support mounted insaid housing, resilient means urging said support upwardly to retractthe cutter from a workpiece, a iluid connection to supply fluid underpressure to the interior of said housing to force the cutter supportdownwardly against the resilient means, a combined buffer and strokeadjuster mounted in said housing and extensible against the upper end ofthe cutter support to adjustably limit said support in its upwardmovement, said bufng means including a reservoir, valve means permittingaccess of air under pressure into said reservoir during the downwardmovement of the cutter support, said valve means being releasable whenthe cutter support reaches the upper end of its movement so as torelease the stored 'air and cushion the cutter support in its upwardmovement.

5. A cutter holding head for a machine tool comprising, a housing, a ramreciprocable in said housing, said ram having a piston at its upper endand supporting a cutter at its lower end. the piston having an elongatedskirt with a pair of diametrically opposed stop lugs thereon, a spacerblock supporting ring adjacent the lower end of the piston and havingspacer blocks thereon in pairs of equal height to be positioned in thepath of said stop lugs and limit downward movement of the piston, andmeans for rotating said ring to bring selected pairs of spacer blocksinto the path of said lugs.

6. The combination in a tool holder wherein a plurality of stops aresuccessively positioned to limit the movement of a tool holding ram, ofmeans for successively locating said stops in ram movement limitingposition comprising; an index cylinder, a plunger reciprocable in saidcylinder, means for reciprocating said plunger, a plurality ofaccurately dimensioned stops, a support for said stops, and 'meansconnecting the plunger to said 'support whereby successive stops arepositioned in ram movement limiting position by actuation of theplunger.

7. In apparatus of the character described, a housing, a tool carryingram supported by said housing, an index plunger, a space blocksupporting ring rotatably mounted on the housing and bearing a pluralityof accurately dlmensioned space blocks, stop means on said ramengageable with a selected space block to limit the downward movement ofthe ram, means carried by the index plunger for rotating said ring apredetermined distance to carry a selected space block into the path ofthe stop means, and means associated with the plunger for limiting therotation of said ring when a selected space block is vpositioned in thepath of the stop means.

8. In a cutter holding head for a machine tool, a support, a fluidoperated tool holding ram mounted upon said support, means normallyretaining said ram in retracted position, a fluid operated indexingmember mounted upon said support, means normally retaining said indexingmember in retracted position, a plurality of spacing blocks moveable bysaid indexing member into a ram movement limiting position, meansnormally retracting the ram and the indexing member, and means forsimultaneously applying uid pressure to said ram and said indexingmember, the fluid operating areas of the ram and indexing members beingso proportioned to the force exerted by their respective retractingmeans that upon application of fluid pressure the movement of the indexmember is substantially completed to position a space block in ramlimiting position before the ram commences to move.

9. A cutter holding head for a machine tool comprising, a housing havinga ram bore and an index bore, a tool carrying ram member mounted in theram bore and extensible to be projected therefrom by fluid pressurewithin the ram bore, an index plunger mounted in the index bore andextensible to be projected therefrom by lluid pressure within `the indexbore, means normally retracting the ram and the index plunger into theirrespective bores, a ring .mounted on said housing for rotation by theprojecting movement o the index plunger, a plurality of space blocks onsaid ring, a lug on said ram engageable with at least one of said spaceblocks for limiting the projecting movement of the ram, 'means forsimultaneously applying fluid pressure to each of said bores to projecteach of the members, the area of the bore and the strength of theresilient means for each member being so proportioned that uponapplication of fluid pressure the projecting movement of the indexplunger is substantially completed before the initial movement of theram.

l0. A pneumatically operable head for supporting a cutter on a machinetool comprising a housing, a cutter support mounted in said housing forreciprocation between extended and retracted positions, means forsupplying uid pressure to said housing to move the cutter support to itsextended position, a bearing means slidably mounted in said housing, aresilient means for acting against said bearing means to urge the cuttersupport toward its retracted position, and means on the cutter supportto engage the bearing means as said support approaches its retractedposition to release the cutter `support from the effect of saidresilient means.

l1. A pneumatically operable head for supporting a cutter on a machinetool comprising a housing, a cutter support mounted in said housing forreciprocation between extended and retracted positions, means forsupplying fluid pressure to said housing to move the cutter support toits extended position, a supporting meansv mounted on said housing, abearing means mounted on said vsupporting means, a resilient means foracting against said bearing means to urge the cutter support toward itsretracted position, and means on the cutter support to engage thebearing means as said cutter support approaches is retracted position torelease the cutter support from the effect of said resilient means.

12. A pneumatically operable head for supporting a cutter on a machinetool comprising a housing, a cutter support mounted in said housing :forreciprocation between extended and retracted positions, means forsupplying iiuid pressure to said housing to move the cutter support toits extended position, a bushing mounted in said housing and having ashoulder thereon, a bearing means slidably mounted in said bushinglimited in movement in the direction of extension of the cutter supportby said shoulder, a resilient means for acting against said bearingmeans to urge the cutter support toward its retracted position, andmeans on the cutter support to engage the bearing means as said cuttersupport approaches its retracted position to release the cutter supportfrom the effect of said resilient means.

13. A tool holder and control therefor for use on a machine tool whichis provided with a table to which a workpiece is secured and comprising,a support, a ram movable in said support to move a cutting tool to aplurality of predetermined cutting positions, means for moving said ramin said support, variable means for limiting the movement of said ram atsaid predetermined cutting positions, and means operable during theprogress of a continuous cutting stroke of the machine sequentiallyvarying said limit means whereby said cutting tool may be moved to oneof the plurality of cutting positions, said means Ifor varying the limitmeans including a pneumatically operated indexing mechanism operativelyconnectable to said limit means in response to predetermined pneumaticpressures, a control assembly pneumatically connected between a sourceof fluid under pressure and said indexing mechanism, regulating meanssecured to the workpiece support in predetermined positions with respectto the workpiece table, said control assembly beingtemporarilyengageable with said regulating means in sequence and substantiallysimultaneously with the arrival of the cutter at predetermined positionson the workpiece to thereby regulate the operation of said controlassembly, indexing mechanism and limit means for effecting a cuttercontrol program for each stroke of the cutter and related to sequentialwork operations to be performed upon spaced surfaces of the workpiece.

14. A cutter holding head and control for a machine tool which includesa table to which a workpiece is secured comprising, a housing adaptedto` be secured to the usual tool supporting pad of the machine suchhousing having a cylindrical opening therein, a cutter supportreciprocable in said opening, means to limit movement or said cuttersupport to a plurality of predetermined cutting positions, said meansincluding a plurality or" accurately dimensioned space blocks, blockengaging means on the cutter support for engagement with a space blockto position the cutter in accordance with the size of the block, andautomatic means for moving the space blocks of varying size into thepath of the block engaging means, said automatic means including atoothed indexing ring secured to said space blocks, a pneumaticallyoperated pawl connectable to and disconnectable from said indexing ringin response to predetermined pneumatic pressures, a pressure controlassembly pneumatically connected to a. source of fluid under pressureand said pawl, and regulating means secured to the workpiece table inpredetermined positions with respect to predetermined areas on theworkpiece, said control assembly including fluid inlet, outlet andventing passages, valves disposed in said inlet and venting passages,and means for actuating said valves in response to temporary engagementwith said regulating means in sequence :and substantially simultaneouslywith the arrival of the cutter at predetermined positions on theworkpiece to thereby regulate the operation of the control assembly,pawl, indexing ring, and limit means for effecting a cutter controlprogram for each cycle of the cutter and related to sequential workoperations tol be performed upon spaced surfaces of the workpiece.

15. A tool supporting head and control for a machine tool having a worksupporting table wherein the cutter may be accurately and rapidlylongitudinally indexed comprising, a tool support, indexing meanscarried by said support, said indexing means comprising a plurality ofdifferent size space blocks, stop means carried by said head forsuccessively engaging said space blocks to thereby position the cutterin accordance with the size of the spaced block engaged, automatic meansincluding an actuating assembly operatively connected to the indexingmeans and to the table and controlled by the movement of the table foreiecting a predetermined relative intermittent engagement of theindexing means with the stop means to sequentially engage the stop meanswith the space blocks of varying sizes as a predetermined cycle ofmachine operations is performed, and means to move the tool supportdownwardly in timed relation with the operation of said actuatingassembly.

16. A cutting head and control for use on a machine tool whereinrelative movement is effected between a cutter and a workpiececomprising, a support, a cutter controlling ram movable on the support,means for alternately extending and retracting the ram to move thecutter toward and away from the workpiece during the cutting stroke,means for limiting the extension of the ram, said limiting meansincluding different size space blocks, and trip means for successivelyresetting the limiting means to a plurality of positions in timedrelation with the changing relative positions of the workpiece andcutter whereby the ram may be extended a variety of distances to machineportions of a workpiece in dlierent planes during a continuous cuttingstroke.

LUTHER E. LEE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 590,051 Weddell Sept. 14, 1897 1,081,932 Smith Dec. 18, 19131,287,342 Knight Dec. 10, 1918 1,430,681 Pierce Oct. 3, 1922 1,451,061Trasch Apr. 10, 1923 2,017,999 West Oct. 22, 1935 2,154,718 Bannon Apr.18, 1939 2,370,286 Berger Feb. 27, 1945

